Shielded electrical connectors are well known. These connectors are used for coupling shielded cables, which are electrical cables in which at least one insulated inner conductor is enclosed by a conductive shielding layer. Where there is a single insulated inner conductor, shielded cables are known as coaxial cables.
Shielded cables are typically used in applications where it is desired to minimise the effect of electrical noise on signals which are being carried in the cables or to reduce the electromagnetic radiation emitted by the cables. The former is particularly important for cables carrying high bandwidth signals which are particularly susceptible to noise. The latter is important for cables carrying high voltages. Shielded cables may be used for carrying analogue or digital signals.
In shielded cables, the shielding is usually in the form of braided strands of copper which surround the inner conductor(s), although other conductive shielding arrangements such as spiral windings of metallic foil and sleeves of conductive polymers are also known. The shielding is usually grounded, although the shielding may in some applications carry signals. In either case, it is important that a shielded electrical connector maintains the shielding and provides a reliable electrical connection for both the inner conductor(s) and the shielding.
In known shielded electrical connectors, such as Bayonet Neill-Concelman connectors, hereinafter referred to as BNC connectors, the shielding connection is provided by a conductive sleeve-like body. The sleeve-like body surrounds a dielectric spacing member, which spacing member accommodates at least one elongate contact pin provided for connecting the inner conductor.
Known shielded electrical connectors are typically coupled to shielded cables by an assembly process in which a crimping tool is used to attach a crimp sleeve to the sleeve-like body of the connector, with the shielding of the cable being trapped between the sleeve-like body and the crimp sleeve. The crimp sleeve serves to provide an electrical connection between the cable shielding and the sleeve-like body of the connector and to mechanically couple the cable to the connector.
A potential problem with shielded electrical connectors of the type described above is that a special tool is required for coupling the connectors to cables, which adds both cost and complexity to the connector assembly process. Moreover, different sized tools are required for different sized cables and connectors. In some applications, crimp tools may need to be periodically calibrated, which may add further considerable expense.